1. Field of the Invention
The present invention is directed to an air pre-cleaner and in particular to an air pre-cleaner which removes heavy particles from the air and which controls the flow of air into the pre-cleaner through the exit for the particles.
2. Description of the Prior Art
One of the serious problems in supplying air to an internal combustion engine is the removal of heavy particles, such as dirt, from the air prior to the mixture of the air with the fuel. The conventional technique for removing these particles has been the placement of a paper or oil filter in the air intake, these filters separating the heavy particles from the air prior to its mixture with the fuel. However, one of the disadvantages of this technique is that the heavy particles accumulate on the air or oil filter and after a period of time the filter must be removed and cleaned or replaced.
In order to overcome this disadvantage, pre-cleaners have been developed which impart a circular motion to the air entering the pre-cleaner. The circular motion creates a centrifugal force on the heavy particles and forces them towards the outer walls of the pre-cleaner. A separator is provided for removing these particles as they move outward. One type of separator is a louvered plate in which the openings in the louvers face the direction of circular motion of the air. The heavy particles pass through the openings in the louver and are removed from the device. The air with the heavy particles removed is then passed through a conventional filtering system and subsequently mixed with the fuel. A device of this type can be found in Pierce, U.S. Pat. No. 3,232,032, for example.
The disadvantage of this type of device for removing the heavy particles is that the engine draws air not only through the pre-cleaner air intake but also through the heavy particle exit and then through the louvers into the engine. This tends to defeat the purpose of the pre-cleaner since the air being drawn into the engine through the particle exit will contain heavy particles and also may tend to pick up some of the heavy particles which have been removed from the air entering the air intake.